I Didnt know whether it was concave or not but i gave t a go anyway, I only had 1500, 2000 and 2500 grit sand paper so it took ages!!!
Heres how it looks:
Thumbscrew to show reflection
Reflection of my Scythe Case fan
I know that going above 600grit is probaly a waste of time but the lowest i had was 1500 so i didnt have much choice
Temps: Dropped by a whopping..........2 degrees!!!
Ben

Heres how it looks:
Thumbscrew to show reflection

Reflection of my Scythe Case fan

I know that going above 600grit is probaly a waste of time but the lowest i had was 1500 so i didnt have much choice

Temps: Dropped by a whopping..........2 degrees!!!

Ben